1. Technical Field
Embodiments of the present invention relate to organic light-emitting diodes.
2. Description of the Related Art
Organic light-emitting diodes (OLEDs) are self-emitting devices having advantages such as wide viewing angles, good contrast, quick response speeds, high brightness, and good driving voltage characteristics. Also, OLEDs can provide multicolored images.
A typical organic light-emitting diode structure includes a substrate, and an anode, a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and a cathode sequentially stacked on the substrate. The HTL, the EML, and the ETL are organic thin films formed of organic compounds.
An operating principle of a typical organic light-emitting diode having the above-described structure is as follows. When a voltage is applied between the anode and the cathode, holes injected from the anode move to the EML via the HTL, and electrons injected from the cathode move to the EML via the ETL. Carriers, such as the holes and electrons, recombine in the EML to generate excitons. When the excitons drop from an excited state to a ground state, light is emitted.